A major effort of the Laboratory Core is to analyze human and mouse plasma and sera for lipoproteins and their component lipids and apolipoproteins. The lipid analyses employ automated micromethod techniques that have been described previously to determine plasma levels of total cholesterol, HDL cholesterol, unesterified cholesterol, tricyglycerols, glycerol blanks, and unesterified fatty acids (1-5). Human plasma LDL and VLDL concentrations are calculated using Freidewald's formula (6). The Laboratory Core also routinely determines, human plasma apolipoprotein concentrations including apoB, apoAI, apoAII, Lp(a), and apoJ. In addition to the measurement of lipids, lipoproteins, and apolipoproteins, the Laboratory Core also determines levels of several other plasma factors related to lipid/lipoprotein metabolism and atherosclerosis, including the plasma concentrations of insulin, glucose, leptin and homocysteine, and the enzymatic activities of lipoprotein lipase, hepatic lipase, and plasma paraoxonase. All of the assays are components of the phenotyping extensively described in Projects 1 and 3 of this grant application and are currently in routine use in our laboratory. The accuracy of our lipid assays is certified by the CDC National Heart, Lung, and Blood Institute Lipid Standardization Program.